This invention relates generally to surgically implanted shunt systems and related flow control valves. More particularly, this invention relates to multiple-membrane one-way flow control valves for controlling the flow of cerebrospinal fluid out of a brain ventricle and preventing back flow of fluid into the brain ventricle.
As is well known in the medical arts, to relieve undesirable accumulation of fluids it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children in which fluids which ought to drain away instead accumulate within the skull and thereby exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is drained away by a catheter inserted into the ventricle through the skull, and the catheter is connected to a tube which conducts the fluid away from the brain to be reintroduced into the vascular system, as by extending through the patient's jugular vein to the atrium portion of the heart. To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the heart.
Many such devices have been previously used, but several of these devices have tended to become obstructed by particulate matter entering the drainage system or by the backward diffusion of blood into the system. Further, some prior devices have included moving parts which tended to adhere to other parts of the device and become immobile. When this occurs, the device itself becomes a barrier in the drainage system, and adds to the problem it is intended to solve.
Moreover, manufacturers have been faced with a dilemma regarding the use of metal components in such valves. Some prior devices have included metal components which tended to interfere with X-ray photography and produce radiation scatter ("sunburst effect") on films taken by computerized axial tomography (CAT) scanning equipment, and such X-ray photography and CAT scanning frequently accompanies the use of surgically implanted flow control valves. However, it is desirable in some instances to be able to ascertain specific information from an implanted device by X-ray photography without having to reopen the patient's skin. For instance, it is sometimes desirable to provide an X-ray detectable marker which can facilitate detection of a separation of drainage tubing from the valve.
Accordingly, there has been a continuing need in the medical arts for convenient and effective devices for controlling the flow of fluid from one part of the human body to another, which devices are relatively inexpensive to manufacture and can be constructed substantially of nonmetallic parts which are not subject to adhering to one another and causing malfunction of the device. Further, such a device is needed which utilizes multiple valve membranes in series for safety and reliability. As will become apparent from the following description, the present invention satisfies these needs and provides other related advantages.